Automatic calculator



lOct. 15, 1935.

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AUTOMATIC CALCULATOR original Filed July 2, 1928 4 sheets-shea 2 INVENTOR ATTORNEYS Oct. l5, 1935. w. J. PAslNsKl AUTOMATIC CALCULATOR Original Filed July 2, 1928 4 Sheets-Sheet 3 dlNvrsmpR Wa//f d. pawns/n M BY Y@ i ATTORNEYS Oct. 15, 1935. w. J, PAslNs-Kl AUTOMATIC CALCULATOR Original Filed July 2. 192,8 4 Sheets-Sheet 4 INVENTOR A. WE1/7221 n/ Paauw/n' BY M @mi ATTORNEYS Patented Oct. 15, 1935 UNITE-D STATES PATENT OFFICE AUTOMATIC CALCULATOR Walter J. Pasinski, Detroit, Mich., assigner to Burroughs Adding Machine Company, Detroit,

Mich., a corporation-of Michigan 28 Claims.

This invention relates to a clearing mechanism for calculating machines, the present application being a division of co-pending application Serial No. 289,865, led July 2, 1928.

The general object of the invention is to provide an improved cancelling or clearing mechanism in a machine of the class described which will operate automatically upon the depression of a key.

Other ,and more particular objects will hereinafter appear.

An lembodiment of the invention is shown in the accompanying drawings in which:

Figure 1 is a plan View of a calculating machine with the cancelling mechanism applied thereto.

Fig. 2 is a side elevation and cross-section of/ said machine showing particularly the cancelling mechanism.

Fig. 3 is a detail View illustrating the key interlocking construction, the parts being shown in normal condition.

Fig. 4 is a side elevation of the cancelling mechanism with the parts in operated position.

Fig. 5 is another detail view of the key interlocking mechanism showing the parts in locking position.

Fig. 6 is a detail side elevation of a portion of the cancelling mechanism shown in Fig. 4.

Figs. 7, 8, and 9 are sections of a portion of the cancelling mechanism showing the parts in different positions, the sections being taken on the line 1 1 of Fig. 4.

Fig. l0 is a partial side elevation and section showing the forward portion of the mechanism of the present invention and certain portions of the cancelling mechanism directly associated with the register.

The cancelling mechanism is shown applied to an automatic calculator in which calculations take place in each order immediately upon depression of a key in that order, the machine being motor operated and entirely automatic.

An understanding of the details of the calculator is not necessary for an understanding of the cancelling mechanism and hence the calculator will be described only very briey. In describing it and in describing the cancelling mechanism the same reference numbers will be used, in so far as possible, as were used in the parent application.

The calculator has a plurality of depressible amount keys l0, any one of which, when depressed, closes a switch 51 that starts an electric motor 40 which, when it operates, rotates a main drive shaft 33 in a counterclockwise direction. Depression of any one of the amount keys in a lgiven bank also acts to connect the differential mechanisms for that bank to a ratchet wheel 41 se that when the motor is operated the differential mechanism is likewise operated. After the differential mechanism has been moved to a position where it is arrested by the depressed amount key said differential mechanism is automatically disconnected from said ratchet wheel and the 10 motor is stopped. The movements of the differential mechanism are imparted to a register 25 at the forward end of the machine and it is this register that must be cleared after a series of calculations. 15

Cancellzng mechanism The cancelling mechanism is entirely automatic and it is set into operation by simply depressing a clearance key |20 illustrated in Fig. 1. 20

The portion of the cancelling mechanism that Aoperates on the register is located at the forward part of the machine and is best shown in Fig. 10. This portion of the mechanism is controlled by an arm |2i which is given a forward and return 25 stroke of movement in clearing as will be described later. This movement of arm |2| rst rocks a shaft |22 counterclockwise and then returns it clockwise to its original position. Fixed to the shaft |22' is an arm 200 having a stud 20| 30 adapted to engage a cam surface 202 on a U- shaped member having two arms 203 and- 204. This member is pivoted at 205 and urged clockwise by a spring 205. The upper end of the arm 203 engages a stud on an arm 201 xed to a shaft 35' 208 that extends across the machine. This shaft has a series of dogs 209 on it, there being one dog for each column or bank of the machine. These dogs are adapted to engage driving pawls 2|0 of which there is one for each bank. During operation of the machine the driving pawls drive the ratchet wheels 2li in a counterclockwise direction and these wheels, in turn, drive the register pinions 25.

When the arm |2| is rocked counterclockwise the U-shaped member 203-20@ is swung in the same direction and the arm 201 is moved clockwise to thereby rock the shaft 208 clockwise. This causes the dogs 200 to engage the pawls 2 i0 to release them from the ratchet wheels 2|| 50 so that the register pinions are free for return to their zero positions under the inuence of a spring andk cam action such as described in Horton Patent No. 1,326,504, to which reference is made for details. The mechanism directly associated with the register and above described has been used for a number of years on the Burroughs calculators and the present invention does not concern its details.

Referring to Fig. 2, the arm |2| is rocked by means of the link |23 having a downwardly extending projection |24 to which one end of a spring |25 is connected. The other end of this spring is connected to a projection |26 on a link |21 having a pin and slot connection with the arm 2|. When the arm 21 is moved forwardly it moves the link |23 forward through the spring |25 and thereby moves the arm |2| forward, the connection being a, yielding one so that, in the event the cancelling mechanism becomes blocked or is sluggish for some reason, the spring will yieldand the parts will not be damaged. The link |21 is moved forward by being connected to the motor drive, the motor being started and such connection being eiected by depression of the key |20.

The key |20 has a stem |30 slidably mounted on studs |3| on the side frame |32 of the machine. The lower end of the stem has a lateral extension |33 to whichis pivoted a pawl |34. This pawl is urged clockwise by a spring |35 into engagement with the edge of a lug 36 of a lateral projection |31 on an inner slide plate |38 mounted on studs |39. The pawl |34 has a shoulder |40 for engaging the lug |36. When the key 20 is depressed the shoulder |40 moves into engagement with lug |36 to move the slide |38 downwardly whereupon a pivoted latch |4| snaps into position to hold the slide depressed, such latching action normally taking place because the end of pawl 4| passes over the lug |36 as shown in Fig. 4. If the key |20 is only partially depressed the latching action also takes place, but in this case the lug 36 is held down by the engagement of a shoulder |42 (Fig. 2) of the latch |4| over lug |36. The spring |35 which urges the pawl |34 clockwise is also connected to the latchV |4| to urge it counterclockwise, one spring serving for both parts. The

slide |38 is moved down against the tension of a spring |43 connected at one end to a stud |44 (Figs. '1 and 8) on the slide and at its other end to a stud on the side plate |32.

. The slide |38 has a rearwardly projecting cam hook |45 having a beveled surface |46 adapted to engage a stud |41 on an arm |48 pivoted at |49 and connected to the bail 58 that controls the starting of the motor, the bail being urged clockwise by the spring 59. When the key |20 is depressed and the slide |38 is moved downwardly, the cam hook |45, acting on the stud |41, cams the arm |48 counterclockwise sumciently to move the bail 58 to effect a starting of the motor. In this manner the motor is started when the cancelling key |20 is depressed.

'Ihe cancelling mechanism is connected to the motor drive by means of a second slide |50 also mounted on the studs |39. The first slide I 38 has a projection |5| to which one end of a spring |52 is connected, the other end of said spring being connected to a projection |53 on slide |50.

When slide |38 is moved down by depression of the cancellation key |20, it pulls the slide |50 down with it through the yielding connection provided by spring |52. The slide |50 has a pin |54 projecting from it through a slot |55 in slide |38 and this pin projects over the cancelling link A|21 as shown in Fig. 8. Accordingly, upon depression of the key |20, the link |21 is swung downward against the tension c1' a. spring |56 which tends to hold it up and rearward, the position of the slides when the key is depressed being shown in Fig. 9. The rear end of the link |21 has a notch |60 in it adapted to engage over a stud |6| on a pivoted arm |62, The arm |62 is urged clockwise by a spring |63 and it has an extension |04 carrying a stud |65 bearing on the edge of a two-faced cam |66 fixed to the shaft 33 which is rotated by the motor. When the key |20 is depressed the link |21 is thus connected to the arm |62 and, since the motor is started by depression of the key |20 as previously explained, the cam |66 rocks the lever |62 counterclockwise which moves the link |21 forward to operate the clearing mechanism. l As the link |23 moves forward with the link |21, a downward projection |10 on it engages a lateral lug |1| on the pawl 34, thereby moving the pawl rzounterclockwise. The edge of the pawl engages against a lateral lug |12 on the latch I4 2 The result is that the .forward movement of the link |23 disables both the pawl |34 and the latch 4| by moving them out of the path orthe lug |36, thereby freeing the slide |38 to permit the spring |43 to return the slide to normal. This 2 frees the arm |48 connected with the motor starting bail 58 and stops the motor. As the slide |38 moves upwardly the bottom edge of its slot |55 contacts the pin |54 and carries it upwardly thereby freeing the link 21. The high surface of the cam |66 having passed the stud |65, the arm |62 is rocked clockwise back to normal by spring |63. The link |21 is moved back by its spring |56 which, near the end of the return stroke of the link, lifts the latter upwardly to disconnect it from the stud |6|. The parts are thus returned to normal and it is to be noted that the zeroizing mechanism is disconnected and the motor stopped independently of the length of time that the cancellation key |20 is held de- 41 pressed. The actuating operation, or forward movement, of the link |21 disconnects the pawl |34 from the lug |36 of the slide |38 thereby disabling the control of slide |38 by key |20. The

slide |38 returns to normal under the iniiuence 4f of its spring and releases link |21 to enable it to be pulled to disconnected position by spring |56. Upward movement of slide |38 also releases the motor starting means including bail 58 so that the latter may move to position to stop the motor. 5(

As long as the key |20 is held depressed, the pawl |34 cannot be reconnected with the slide |38 and hence a second operation of the zeroizing mechanism or a continuous operation of the motor cannot take place. It is necessary to release the cancellation key |20 and to give it a second depression in order to get a second operation of the zeroizing mechanism.

The cam |66 is constructed so that its high surfaces will act on the stud |65 twice during one revolution of the shaft 33. The purpose of this is to secure a quick action so as to waste as little time in cancelling operations as possible.A In the event the notch |60 in the link |21 is not immediately over the stud |6| when the key |28 is depressed, the parts will not be immediately connected together but they will be connected very quickly. Depression of the key starts the motor' which rotates the cam |66 and gives the arm |62 a stroke of movement. As the key is depressed the slide |38 moves downwardly and puts a tension on spring |52 to urge the slide |50 downwardly' to cause its pin |54 to engage the top of the link |21 thereby urging the rear 75 end of the latter downwardly. If the slot |60 and the stud |6| are in alignment, the link |21 is immediately connected to arm |62. If they are not in alignment the slides |38 and 50 assume the position shown in Fig. 8. The slide |38 moves down but the slide |50 is retained upward by link |21. The rear end of link |21 rides on the stud |6| until the arm |62 is returned to its rearward position whereupon the notch |60 snaps over the be blocked in any way, the linkl |21 moves forward without moving the link |23 forward, the spring |25 stretching and the parts assuming the position illustrated in Fig. 6. When this occurs a latch |80, urged counterclockwise by aspring |8I,

' latches behind a shoulder |82 on the link |21 and holds the link in its forward position. Since the link |23 is not moved forward under these conditions the latch |4| remains in position over the lug |36 and the motor continues to. operate to repeatedly oscillate the link |21, the link being returned each time by the spring |25. This oscillation of the link |21 and the continued running of the motor indicates to the operator that something is wrong. Besides which the keys will be found locked, as will be later explained. The link |21 can oscillate without being disconnected from the pin |6| .on arm |62 owing to the fact that the notch |60 allows for some play of the parts and owing further to the fact that the shoulder |82 is located so that when the link |21 is in its farthest forward position, the shoulder is slightly forward of the latch |80. The link |21 may thus have a short oscillatory movement without being disconnected from arm |62 which latter does not return to its fully returned position, but returns to such a position that the cam |66 gives the arm a short oscillatory movement. When the difficulty in the cancelling mechanism has been removed, the link |23 will snap forward under the tension of its spring |25, whereupon a raised projection |83 on the link |23 cams the latch |80 upward to release the link, |21 to permit the latter to be moved back to normal under the influence of its spring |56. During normal operations, when there is no difficulty with the cancelling mechanism the raised projection |83 moves forward at the same time that the two links |23 and |21 are moved forward and it disables the latch |80 at the end of the forward stroke to prevent said latch from becoming effective to holdv the link |21 forward.

Means for locking amount keys while cancellation takes place pivoted shaft |96` This shaft extends across the rear of the machine and it has a series of slots |91 forming a series of semi-circular shaft sections which are aligned with the rearmost of the key interlocking pendants |98 illustrated in Figs. 3 and 5. These pendants are of the fami- 6 liar type used in the Burroughs calculator, the same being illustrated and described in Horton Patent No. 1,243,839. There is one of these pendantsbetween each two keys and one to the rear of the 9 key and their lower ends are spaced l0 so that there is just enough clearance to perl mit one key to be depressed at a time. Whenever a key is depressed the pendants are moved together so closely that there is no space to depress a second key. f l When the cancellation key |20 is depressed and the slide |50 is moved downwardly the bell crank lever |92|93 is moved clockwise which rocks the shaft |96 clockwise fromits Fig. 3 to its Fig. position. The edges of the slots |81 swing 20 the rear pendants |98 forward and move all of them in each of the rows so close together that none of the keys in any of the banks can be depressed. In this manner, as soon as the cancellation key is depressed, all of the amount 25v keys are locked against depression. Also, when one of the amount keys is depressed, the shaft |96 is blocked against turning which prevents depression of the cancelling key |20 when an t amount key is depressed.

When the cancellation key |20 is released and the slide |38 is moved upwardly under the influence of its spring |43, said slide engages the pin |54 on the slide |50 and moves the latter upwardly which cams the bell crank lever |92-I93 counterclockwise to swing the shaft |96 counterclockwise thereby releasing the interlocking pendants |98 and freeing the amount keys.

I claim:

1. A calculating machine having a register, a zeroizing mechanism therefor, a normally inactive motor for driving said zeroizing mechanism, a slidable means urged toward a normal position, a depressible key for moving said slidable means away from its normal position, a latch 4K5I for holding said slidable means in the position to which it is moved, a linkage mechanism for connecting said motor to said zeroizing mechanism, connections operated by said slidable means as it is moved to start said motor, said slidable means also having a portion acting to move said linkage mechanism to position for connection to said motor, and means carried by said linkage mechanism operating to release said latch during the movement of said linkage mechanism to thereby release said slidable means to permit it to return to normal, said slidable means, in returning to normal, acting to release said motor starting mechanism to stop said motor and to release said link-age mechanism to permit it to be disconnected from said motor.

2. A calculating machine having a register,

a zeroizing mechanism therefor, a motor for driving said zeroizing mechanism, a linkage mechanism between said motor and zeroizing mechanism, said linkage mechanism including one link connected to said zeroizing mechanism and a second link adapted to be driven by said motor,

a yielding connection between said links, a slidable means urged toward av normal position, a depressible key having a pivoted pawl releasably connected to said slidable means so that, upon depression of said key, said slidable means will be moved away from normal, connections op'- erated by said slidable means as it moves away i'rom normal causing said motor to drive the link connected to said motor, said iirst link having a portion acting when it is moved by said second link to disable said pawl.

3. A clearing mechanism for calculating machines oi' the class described comprising, in combination with a machine having a register and a zeroizing mechanism therefor, a power driving means, normally disconnected operating connections between said power driving means and said zeroizing mechanism, a manipulative member for conditioning said connections to connect said zeroizing mechanism to said driving means, and means operating automatically as said zeroizing mechanism is operated to disconnect said operating connections irrespective of the position of said manipulative member. 4

4. A clearing mechanism for calculating machines of the class described comprising, in combination with a machine having a register and a zeroizing mechanism therefor, a power driving means, normally disconnected operating connections between said power drive and said zeroizing mechanism, a manipulative member for conditioning said connections to connect said zeroizing mechanism to said power driving means, and means actuated by said operating connections as the same are moved to complete the operation o! said zeroizing mechanism for automatically disconnecting said zeroizing mechanism from said power drive independently of the position of the manipulative member.

5. A clearing mechanism for calculating machines of the class described comprising, in combination with a machine having a register and a zeroizing mechanism therefor, a power driving means, operating connections between said power driving means and said zeroizing mechanism urged to disconnected position, a manipulative member for moving said connections to connected position, a latching means for latching said connections in connected position, and means operating automatically to release said latching means as said operating connections complete their actuating movement in their operation of the zeroizing mechanism.

6. A clearing mechanism for calculating machines of the class described comprising, in ccmbination with a machine having a register and a zeroizing mechanism therefor, a power driving means, a link for connecting said zeroizing mechaniam to said power driving means, said link being urged to disconnected position, means conditioned by a manipulative member for moving said link to and holding it in connected position, a latch for holding said means in the position to which it is moved by said manipulative member, and means operated by said link as it completes its actuating movement .in operating said zeroizing mechanism for automatically releasing said latch.

7. A clearing mechanism for calculating machines of the class described comprising, in combination with a machine having a register and a zeroizing mechanism therefor, a normally inactive motor normally disconnected operating connections between said zeroizing mechanism and motor, means conditioned by a manipulative member for automatically starting said motor and connecting said zeroizing mechanism to said motor, and means operating automatically and independently of the position of said manipulative member to stop said motor and disconnect it from said zeroizing mechanism after the latter has been operated.

nections as the same complete their actuating movement in operating said zeroizing mechanism for automatically stopping said motor and disconnecting said operating connections from said motor independently oi the position of said mampulative member.

9. A clearing mechanism for calculating machines of the class described comprising, in combination with a machine having a register and a zeroizing mechanism therefor, a normally inactive motor, operating connections between said zeroizing mechanism and motor urged to disconnected position, motor starting means urged to non-starting position, controlling means conditioned by a manipulative member for moving said operating connections to connected position and said motor starting means to starting position, a latch for holding said controlling means in the position to which it is moved, and means operating automatically after said zeroizing mechanism has been actuated to release said latch to release said controlling means to enable said motor starting means to move to non-starting position and said operating connections to move to disconnected position.

10. A clearing mechanism for calculating machines of the class described comprising, in combination with a machine having a register and a zeroizing mechanism therefor, a normally inactive motor, operating connections between said zeroizing mechanism and motor urged to disconnected position, motor starting means urged to non-starting position, controlling means conditioned by depression of a clearance key for moving said operating connections to connected position and said motor starting means to starting position, a latch for holding said controlling means in the position to which it is moved by said clearance key, and means actuated by said operating connections as the latter complete their actuating movement for releasing said latch.

11. A clearing mechanism for calculating machines of the class described comprising, in combination with a machine having a register and a zeroizing mechanism therefor, a power driving means, normally disconnected operating connections between said zeroizing mechanism and power driving means, a clearance key controlling said connections to condition them to connect said zeroizing mechanism to said power drive, and means operating automatically to disable the control of said operating connections by said clearance key until said operating connections have returnedl to normal after having been moved to actuate said zeroizing mechanism.

1.2. A clearing mechanism for calculating machines of the class described comprising, in combination with a machine having a register and a zeroizing mechanism therefor, a power driving means, normally disconnected operating connections between said powendriving means and said zeroizing mechanism, a manipulative member releasably connected to said connections for conditioning them to connect said zeroizing mechanism to said driving means, and means operated Cal automatically by said connections as they move to operate said zeroizing mechanism for automatically disconnecting said manipulative member from said operating connections until said operv ating connections return to normal.

13. A clearing mechanism for calculating machines of the class described comprising, in combination with a machine having a register and a zeroizing mechanism therefor a power driving means, normally disconnected operating connections between said zeroizing mechanism and power driving means, said connections having a forward and a return stroke of movement in operating said zeroizing mechanism, a clearance key for controlling said operating connections to condition them to connect said zeroizing mechanism to said power drive, and means operated by said connections during their forward stroke for automatically disabling the control of said operating connections by said clearance key until said operating connections have completed their return stroke.

14. A clearing mechanism for calculating machines of the class described comprising, in combination with a machine having a register and a zeroizing mechanism therefor, a power driving means, normally disconnected operating connections between said power driving means and said zeroizing mechanism, a manipulative member for controlling said connections to condition them to connect said zeroizing mechanism to said driving means, and means operating automatically as said connections are moved to operate said zeroizing mechanism for automatically disconnecting said zeroizing mechanism from said power drive and automatically disabling the control of said connections by said manipulative member until said connections have returned to normal.

15. A clearing mechanism for calculating machines of the class described comprisingin combination with al machine having a register and a zeroizing mechanism therefor, a normally inactive motor, normally disconnected operating connections between said zeroizing mechanism and motor, controlling means conditioned by a' manipulative member for starting said motor and connecting said zeroizing mechanism to said motor, and means operating automatically, after said operating connections have been moved to actuate said zeroizing mechanism, to stop said motor, to automatically' disconnect said operating connections from said motor, and to automatically disable the control of said connections by said manipulative member until said connectionsihave returned to normal position.

16. A clearing mechanism for calculating ma.- chines of the class descrmed comprising, in combination with a machine having a register and a zeroizing mechanism therefor, a power driving means, normally disconnected operating connections between said zeroizing mechanism and power driving means, said connections being adapted to be given a forward and a return stroke of movement in operating said zeroizing mechanism and having a portion that is movable when said zeroizing mechanism is blocked at the time said connections are moved, a clearance key for conditioning said connections to connect said zeroizing mechanism to said driving means, means operating automatically during the forward stroke of said connections to disable the control of said connections by said clearance key until the return of said connections to normal, and means preventing the return of said connections to normal when said zeroizing mechanism is not operated during the forward stroke of said operating connections. l

17. A clearing mechanism for calculating machines of the class described comprising, in combination with a machine having a register and a zeroizing mechanism therefor, a power driving means, a normally disconnected operating connection between said zeroizing mechanism and power driving means including two links yieldingly connected together, the first of said links beingr adapted to be connected to said driving means and the second being connected to said zeroizing mechanism, a clearance key for conditioning said operating connections to connect said zeroizing mechanism to said power driving means, means operated automatically by said second link, which is connected to said zeroizing mechanism, for disabling the control of said operating connections by said clearance key when said second link is moved to operate said Zeroizing mechanism, a latch operable to hold said rst link in its forward position, and means carried by said second link for releasing said latch when said second link moves to a position to operate said zeroizing mechanism.

18. In a machine of the class described, a plurality of depressible amount keys, a register, clearing mechanism for said register, power driving means for said clearing mechanism, driving connections conditioned by depression of a clearance key for connecting said power driving means to said clearing mechanism to move the latter, means conditioned by depression of said clearance key for locking the amount keys against depression, and means operated by said driving connections as said register is cleared for releasing said locking means.

19. In a machine of the class described, a plurality of depressible amount keys, a register, a clearing mechanism for said register, power driving means for said clearing mechanism, driving connections conditioned by depression of a clearance key for connecting said power driving means to said clearing mechanism for a clearing oper-- ation, latching means for holding said driving connections in the position to which they are -moved by said clearance key, means conditioned by said clearance key at the same time that said driving connections are conditioned for locking said amount keys' against depression, said key 50 locking means being held in locking position by said latching means after being moved to locking position, and means for automatically releasing said latching means as said register is cleared.

20. In a machine of the class described, a calculating mechanism, a register, clearing mechanism for said register, power driving means, a member oscillated by said driving means, linkage mechanism connected to said clearing mechanism, said linkage mechanism having a link adapted to be positioned in the path of said oscillating member but being normally held out o f the path of said member, and means operable by a manipulative member for moving said link into the path of said oscillating member to thereby cause said power drive to operate said clearing mechanism.

21. In a machine of the class described, a calculating mechanism, a register, clearing mechanism for said register, power driving means, a member oscillated by said driving means, linkage mechanism connected to said clearing mechanism, said linkage mechanism having a link adapted to be positioned in the path of said oscillating member but being normally held out of the path of said member, means operable by depression of a clearance key for moving said link into the path of said oscillating member to thereby cause said power drive to operate said clearing mechanism, and means automatically releasing said link to permit the same to return to normal after said clearing mechanism has been operated.

22. In a machine of the class described, a calculating mechanism, a register, clearing mechanism for said register, power driving means, a cam rotatable by said powei driving means. a pivoted lever carrying a roller adapted to be engaged by said cam, a linkage mechanism connected to said clearing mechanism, said linkage mechanism having a link adapted to be engaged by said pivoted lever but being normally held in a disengaged position, and means. operable by a clearance key for moving said link into the path of said pivoted lever.

23. In a machine of the class described, a calculating mechanism, a register, clearing mechanism for said register, power driving means, a cam rotatable by said power driving means, a pivoted lever carrying a roller adapted to be engaged by said cam, a linkage mechanism connected to said clearing mechanism, said linkage mechanism including a link having a shoulder adapted to be engaged by. a second roller on said pivoted lever, means normally holding said link out of the path of said second roller, a clearance key having connections operable, upon depression of said key, to move said link so that its shoulder is in the path of said second roller, and means operating automatically as said linkage mechanism is moved to operate the clearing mechanism to cause said link to be returned to its normal position with its shoulder out of the path of said second roller.

24. In a calculating machine of the class described, a plurality of depressible amount keys, a register, clearing mechanism movable to clear said register including portions movable during a clearing movement even though said register is not cleared by said movement, and means locking the amount keys against depression when movement of the clearing mechanism does not clear said register.

25. In a machine of the class described, a plurality of depressible amount keys, a register clearing mechanism for the register, power driving means for said clearing mechanism, driving connections for connecting said power drive to said clearing mechanism to operate the same, said driving connections including portions movable by said power drive for a clearing movement even though said register is`blocked against clearing, and means locking the amount keys against de- 5 pression when the movement of said driving connections by said power drive does not clear said register.

26. In a machine of the class described, a plurality of depressible keys, a register, a clearing 10 mechanism for said register, a power driving means for said clearing mechanism, driving connections conditioned by depression of a clearance key for connecting said power driving means to saidv clearing mechanism for a clearing opera- 15 tion, locking means conditioned simultaneously with said driving connections for locking the amount keys against depression, and latching means for holding said driving connections in connected position and said locking means 1h20 locked position, said driving connections including portions normally releasing said latching means as the register is cleared but having provisions for permitting operation of the connections without releasing said latching means when said register is blocked against clearing, said locking means preventing said amount keys from being depressed as long assaid latching means is not released.

27. A key responsive calculator of the class described having a register, a clearing mechanism for said register adapted to clear said register by a single stroke of operation, a power driving means, a clearance key, and means conditioned by depression of said clearance key for causing said power driving means to automatically give said clearing means a single stroke of operation only irrespective oi the length of time that the key is held depressed.

28. A key responsive calculator of the class described having a register, a clearing mechanism for said register adapted to clear said register by a single stroke of operation, a normally inactive motor driving means, a clearance key, and means conditioned by depression of said clearance key for starting said motor, for causing said motor to give said clearing mechanism a single stroke of operation only regardless of how long the clearance key is held depressed, and for then automatically causing said motor to be stopped after said clearing mechanism has been operated.

WALTER J. PASINSKI. 

